Conventional liquid crystal display panels mainly have a pair of glass substrates, a liquid crystal layer between these substrates, electrodes on each of these glass substrates, and a polarizing plate attached to each glass substrate. In this type of liquid crystal display panel, light from the backlight passes through the polarizing plates and liquid crystal layer and facilitates display of an image by the contrast on the screen. Much of the light from the backlight, however, is lost due to absorption or reflection by the time the light reaches the display screen, which is a factor in reducing light use efficiency. In particular, light loss caused by the polarizing plates has a large effect on a reduction in light use efficiency.
The reduction in light use efficiency in a conventional TN (twisted nematic) type liquid crystal display panel will be explained using FIG. 20. FIG. 20 shows the path of light that has entered a conventional liquid crystal display panel. The incident light in the drawing comes from the backlight (not shown), for example.
The incident light passes through the rear polarizing plate and becomes linearly polarized, but light loss occurs at this time. The linearly polarized light is twisted by the liquid crystal layer and passes through the front polarizing plate. Absorption at the polarizing plate optical axis, deviations in the twisting stemming from the degree of accuracy in liquid crystal orientation control, or the like causes a slight loss of light when the light passes through the front polarizing plate, even if the liquid crystal display panel is performing white display.
Patent Document 1 discloses a transflective display (FIGS. 21(a) and 21(b)) that transmits and reflects light that has entered a suspended layer containing a plurality of particles. In this transflective display, display is performed by voltage being applied to platelet-shaped metal particles, for example, in order to orient the metal particles in a vertical or horizontal direction to allow light from the backlight to pass through or to reflect external light. With this configuration, the polarizing plates can be omitted, and light use efficiency can be increased as compared to a liquid crystal display panel.
Patent Document 2 discloses an optical device (see FIG. 22) that contains polymer flakes suspended in a host. The optical device selectively changes the optical characteristics thereof by changes in the applied voltage.
When using nematic liquid crystal as the host, for example, if alternating voltage is applied to the optical device, the host will align horizontally with respect to an electric field E and the flakes will align in the direction to which the host is aligning.
In this manner, the optical device in Patent Document 2 can selectively change optical characteristics by a change in applied voltage.